The field of this invention is that of electrical circuits using semiconductor devices and the invention relates more particularly to mounting semiconductors and electrical circuits with improved reliability and density.
Semiconductor devices such as diodes or integrated circuits or the like are conventionally formed of materials characterized by relatively low coefficients of thermal expansion and some devices such as power semiconductors generate significant amounts of heat when electrically energized. Accordingly when such devices are thermally cycled while fixedly attached to printed circuit boards, differences in thermal expansion between the devices p.c. board materials can cause detachment of the devices from the boards. Similarly build up of heat within the semiconductor devices or p.c. boards tends to limit the densities with which the devices can be accommodated in p.c. board units. As a result a number of different semiconductor mounting arrangements using composite metals have been proposed for providing more reliable device mounting and improved heat-dissipation from the devices. However, although such previously known arrangements have involved substantial expense, they have been less than fully satisfactory in a number of applications in providing reliable device mounting while also providing adequate heat-dissipation from the devices.